Methods for reducing fabric drying time and fabrics with improved properties

ABSTRACT

Methods for reducing the trying time of fabric comprise treating the fabric with a treatment composition comprising formaldehyde, catalyst for crosslinking the formaldehyde with natural fibers in the fabric, and silicone elastomer or a precursor thereof, and heating the treated fabric to effect crosslinking of the formaldehyde. Fabrics having reduced drying times, particularly in combination with additional advantageous properties, are produced.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 37 U.S.C. §119(e) to U.S.Provisional Application Serail No. 60/192,902, filed Mar. 29, 2000(Attorney Docket No.8010P).

FIELD OF THE INVENTION

[0002] This invention relates to methods for reducing the drying time offabrics, particularly fabrics containing natural fibers such as cotton,rayon and the like, and, in further embodiments, to methods for reducingthe drying time of fabrics while providing the fabrics with good waterabsorbency, durable press and/or shrinkage resistance. This inventionalso relates to natural fabrics which exhibit reduced drying time, and,in further embodiments, to natural fabrics which exhibit reduced dryingtime in combination with good water absorbency, good durable pressproperties and/or shrinkage resistance.

BACKGROUND OF THE INVENTION

[0003] Many fabrics, particularly fabrics comprising natural fibers, donot possess durable press (or “wash and wear” or “smooth-dry”)performance or dimensional stability, i.e., shrinkage resistance.Cellulosic fabrics such as cotton have been treated with aminoplastresins, including N-methylol cross-linking resins such as dimethyloldihydroxyethyleneurea (DMDHEU) or dimethylol propylcarbamate (DMPC), toimpart durable press properties, as disclosed, for example, in theMartin et al U.S. Pat. No. 4,521,176. Unfortunately, many reactedaminoplast resins break down during storage, thus releasingformaldehyde. The formaldehyde release may occur not only throughout thepreparation of the fabric but also during garment-making. Further,garments or fabrics treated with aminoplast resins may releaseadditional formaldehyde when stored under humid conditions. Aminoplastresins may also hydrolyze during washing procedures, resulting in a lossof the durable press performance. Additionally, aminoplast resins tendto give fabric a harsher handle, that is, make the fabric feel lesssoft. As the resins make the fabric feel less soft, the fabric must betreated with additional softeners. Unfortunately, the softeners tend tomake fabric hydrophobic although it is often preferred that the fabrichave hydrophilic properties for consumer comfort.

[0004] Cellulosic fibers have also been cross-linked with formaldehydeto impart durable press properties. For example, the Payet U.S. Pat.Nos. 3,960,482, 3,960,483, 4,067,688 and 4,104,022 disclose durablepress processes which comprise impregnating a cellulosicfiber-containing fabric with an aqueous solution comprising a catalyst,and, while the fabric has a moisture content of above 20% by weight,exposing the fabric to formaldehyde vapors and curing under conditionsat which formaldehyde reacts with the cellulose. The Payet U.S. Pat. No.4,108,598 discloses a process which comprises treating cellulosicfiber-containing fabrics with an aqueous solution of formaldehyde and acatalyst, heat curing the treated fabric by introducing the fabric intoa heating zone, and gradually increasing the temperature of the heatingzone, thereby increasing the temperature of the heated fabric to preventthe loss of an amount of formaldehyde which will reduce the overallextent of curing. The Payet U.S. Pat. No. 5,885,303 also discloses adurable press process for cellulosic fiber-containing fabrics. Theprocess comprises treating the fabric with an aqueous solution offormaldehyde, a catalyst capable of catalyzing the cross-linkingreaction between formaldehyde and cellulose, and an effective amount ofa silicone elastomer to reduce loss in tear strength in the treatedfabric. Formaldehyde is generally less expensive than aminoplast resins,and formaldehyde treatment of cellulosic fabrics typically results indurable press properties which are more durable than those obtained byaminoplast resins.

[0005] Rayon garments are desirable by consumers for a variety ofreasons. However, many durable press treatment processes that have beenprovided for cotton cellulose fabrics have not been suitable for rayonfabrics. Although rayon and cotton are both cellulosic fibers, theyreact very differently from one another. Particularly, rayon-containingfabrics exhibit significant shrinkage when subjected to aqueous washingor laundering and therefore generally require dry cleaning as opposed towashing in an aqueous environment.

[0006] The copending Payet application Ser. No. 09/163,319 disclosesprocesses for providing rayon fabrics with durable press propertieswherein a rayon fiber-containing fabric is treated with an aqueousmixture containing a high concentration of formaldehyde and a catalystcapable of catalyzing the cross-linking reaction between formaldehydeand the rayon, and the treated fabric is heat cured. Payet disclosesthat the fabric may be washed or laundered in an aqueous system and doesnot shrink substantially on aqueous washing. Additionally, a siliconeelastomer may be employed to reduce loss in tear and tensile strength inthe treated fabric.

[0007] An important feature of cellulose fabrics, both cotton and rayonparticularly, is that they are naturally hydrophilic, and thereforeabsorb moisture. Typically, garments made of fabrics which arehydrophilic are more comfortable for wear and therefore are preferred byconsumers over garments which are formed of hydrophobic, non-moistureabsorbing fabrics. However, many conventional resin-based fabrictreatments for improving durable press and/or for reducing shrinkage ofcellulose fabrics, and particularly for cotton and rayon fabrics, alsorequire the use of silicone softeners which inhibit the natural waterabsorbency of the cellulose fibers and render the fabrics hydrophobic.Such fabrics are therefore not preferred for garment use owing to theirreduced ability or substantial inability to absorb moisture.

[0008] On the other hand, many hydrophilic fabrics retain water and aredifficult to dry. Such fabrics typically require a greater amount ofenergy to thoroughly dry, resulting in increased care costs to consumersand to industries which perform large scale garment washing, for examplethe rental uniform industry. Even certain fabrics which have hydrophobicsurface properties retain large amounts of water and are difficult todry.

[0009] Accordingly, there is a continuing need to further improveindividual characteristics of fabrics containing natural fibers, forexample cotton and rayon, to improve the overall combinations ofproperties exhibited by such fabrics, and to reduce care costsassociated with laundering of such fabrics.

SUMMARY OF THE INVENTION

[0010] Accordingly, it is an object of the present invention to obviateproblems of the prior art. It is a further object of the presentinvention to provide fabrics containing natural fibers and exhibiting anadvantageous combination of properties. It is yet a further object ofthe present invention to provide fabrics containing natural fibers andhaving reduced drying times, and optionally exhibiting one or more ofgood water absorbency, good durable press properties and/or shrinkageresistance. It is a further object of the present invention to reducecare costs associated with laundering of such fabrics. It is a relatedobject to provide methods for preparing fabrics which exhibitadvantageous combinations of properties and which are suitable foraqueous washing or laundering.

[0011] These and additional objects are provided by the methods andfabrics of the invention. In one embodiment, the invention is directedto methods for reducing the drying time of fabric, which methodscomprise treating the fabric with a treatment composition comprisingformaldehyde, catalyst for crosslinking the formaldehyde with naturalfibers in the fabric, and silicone elastomer or a precursor thereof, andheating the treated fabric to effect crosslinking of the formaldehyde.In another embodiment, the invention is directed to methods for reducingthe drying time of fabric while providing the fabric with good waterabsorbency and durable press properties, which methods comprise treatingthe fabric with a treatment composition comprising formaldehyde,catalyst for crosslinking the formaldehyde with natural fibers in thefabric, and silicone elastomer or a precursor thereof, and heating thetreated fabric to effect crosslinking of the formaldehyde. In yetanother embodiment, the invention is directed to methods for reducingthe drying time of fabric while providing the fabric with good waterabsorbency and shrinkage resistance properties, which methods comprisetreating the fabric with a treatment composition comprisingformaldehyde, catalyst for crosslinking the formaldehyde with naturalfibers in the fabric, and silicone elastomer or a precursor thereof, andheating the treated fabric to effect crosslinking of the formaldehyde.In yet additional embodiments, the invention is directed to fabricscomprising natural fibers, having a crosslinked formaldehyde treatmentand being provided with a silicone elastomer, wherein the fabricexhibits a reduced drying time and does not comprise 100% cotton, and tofabrics comprising rayon fibers and exhibiting a reduced drying time.

[0012] The methods of the invention are advantageous in providingfabrics which exhibit reduced drying time, particularly in combinationwith other desirable properties, for example good water absorbency,durable press properties and/or shrinkage reduction.

[0013] These and additional aspects, objects and advantages of theinvention are more fully described in the detailed description.

DETAILED DESCRIPTION

[0014] The present invention is directed to methods for providingfabrics, particularly fabrics comprising natural fibers, with reduceddrying time. Within the context of the present specification, the term“reduced drying time” means a reduction in the ability to retain waterand, therefore, a reduction in the time required to dry a sample of aparticular fabric as compared with an untreated sample of the fabricand/or as compared with a conventional aminoplast resin-treated sampleof the fabric. An untreated sample of the fabric refers to a sample ofthe fabric which does not have any chemical finishing treatment thereon.In specific embodiments, the methods of the invention provide fabricswith drying times which are from about 30% to about 55% less than thedrying times of untreated fabric. In further embodiments, the methods ofthe invention provide fabrics with drying times which are from about 10%to about 45% less than the drying times of conventional aminoplastresin-treated fabric. In selected embodiments, the invention is directedto methods for providing fabrics, particularly fabrics comprisingnatural fibers, with reduced drying time in combination with one or moreof good water absorbency, good durable press properties and/or shrinkageresistance. This invention also relates to fabrics which have reduceddrying time, particularly in combination with one or more of good waterabsorbency, good durable press and/or shrinkage resistance, and whichcan be subjected to aqueous laundering.

[0015] Within the context of the present specification, reference to afabric's ability to retain water refers to the total amount of waterwhich is absorbed by the fabric, i.e., the load, and which must beremoved to dry the fabric. Thus, the reduction in a fabric's drying timeis a result of a reduction in the amount of water the fabric absorbs.This reduction in the amount of water which the fabric absorbs is to becontrasted with the rate at which a fabric will absorb surface water.The rate at which a fabric absorbs surface water is a measure of itshydrophilic/hydrophobic qualities, with high absorption rates indicatinghydrophilic fabric and low absortion rates indicating hydrophobicfabric. Surprisingly, the methods of the present invention providefabrics with reduced drying time, for example as a result of reducedwater retention, while maintaining or providing good hydrophiliccharacteristics, i.e., high rates of water absorbency.

[0016] The fabrics employed in the present invention preferably comprisenatural fibers. As used herein, “individual fiber” refers to a shortand/or thin filament, such as short filaments of cotton as obtained fromthe cotton boll, short filaments of wool as sheared from the sheep,filaments of cellulose or rayon, or the thin filaments of silk obtainedfrom a silkworm cocoon. As used herein, “fibers” is intended to includefilaments in any form, including individual filaments, and the filamentspresent in formed yams, fabrics and garments.

[0017] As used herein, “yarn” refers to a product obtained when fibersare aligned. Yams are products of substantial length and relativelysmall cross-section. Yarns may be single ply yams, that is having oneyarn strand, or multiple ply yams, such as 2-ply yam which comprises twosingle yarns twisted together or 3-ply yarn which comprises three yarnstrands twisted together. As used herein, “fabrics” generally refer toknitted fabrics, woven fabrics, or non-woven fabrics prepared from yarnsor individual fibers, while “garments” generally refer to wearablearticles comprising fabrics, including, but not limited to, shirts,blouses, dresses, pants, sweaters and coats. Non-woven fabrics includefabrics such as felt and are composed of a web or batt of fibers bondedby the application of heat and/or pressure and/or entanglement.“Textiles” includes fabrics, yarns, and articles comprising fabricsand/or yams, such as garments, home goods, including, but not limitedto, bed and table linens, draperies and curtains, and upholsteries, andthe like.

[0018] As used herein, “natural fibers” refer to fibers which areobtained from natural sources, such as cellulosic fibers and proteinfibers, or which are formed by the regeneration of or processing ofnatural occurring fibers and/or products. Natural fibers are notintended to include fibers formed from petroleum products. Naturalfibers include fibers formed from cellulose, such as cotton fiber andregenerated cellulose fiber, commonly referred to as rayon, or acetatefiber derived by reacting cellulose with acetic acid and aceticanhydride in the presence of sulfuric acid. As used herein, “naturalfibers” are intended to include natural fibers in any form, includingindividual filaments, and fibers present in yarns, fabrics and othertextiles, while “individual natural fibers” is intended to refer toindividual natural filaments.

[0019] As used herein, “cellulosic fibers” are intended to refer tofibers comprising cellulose, and include, but are not limited to,cotton, linen, flax, rayon, cellulose acetate, cellulose triacetate,hemp and ramie fibers. As used herein, “rayon fibers” is intended toinclude, but is not limited to, fibers comprising viscose rayon, highwet modulus rayon, cuprammonium rayon, saponified rayon, modal rayon andlyocell rayon. “Protein fibers” are intended to refer to fiberscomprising proteins, and include, but are not limited to, wools, such assheep wool, alpaca, vicuna, mohair, cashmere, guanaco, camel and llama,as well as furs, suedes, and silks.

[0020] As used herein, “synthetic fibers” refer to those fibers whichare not prepared from naturally occurring filaments and include, but arenot limited to, fibers formed of synthetic materials such as polyesters,polyamides such as nylons, polyacrylics, and polyurethanes such asspandex. Synthetic fibers include fibers formed from petroleum products.

[0021] Fabrics for use in the present invention preferably comprisenatural fibers, which natural fibers may be included in any form,including, but not limited to, in the form of individual fibers (forexample in nonwoven fabrics), or in the form of yarns comprising naturalfibers, woven or knitted to provide the fabrics. Additionally, thefabrics may be in the form of garments or other textiles comprisingnatural fibers. The fabrics may further comprise synthetic fibers.Preferably, the fabrics comprise at least about 20% natural fibers. Inone embodiment, the fabrics comprise at least about 50% natural fiberssuch as cotton fibers, rayon fibers or the like. In another embodiment,the fabrics comprise at least about 80% natural fibers such as cottonfibers, rayon fibers or the like, and in a further embodiment, thefibers comprise 100% natural fibers. Fabrics comprising cellulose fiberssuch as cotton and/or rayon are preferred for use in the presentinvention.

[0022] While not being bound by theory, it is believed that when naturalfibers are treated with a composition comprising formaldehyde and acatalyst capable of cross-linking formaldehyde with a natural fiber, achemical modification of the natural fibers occurs. It is believed thatthe formaldehyde reacts chemically with the natural fibers to cross-linkthe individual polymer chains of the natural fibers. The formaldehydetreatment also provides durable press properties and/or dimensionalstability, i.e., reduced shrinkage. In accordance with the presentmethods, a silicone elastomer or precursor thereof is included in theformaldehyde treatment and the fabrics surprisingly exhibit the reducedability to retain water, i.e., the reduced drying time. The combinationof the formaldehyde-silicone elastomer treatment also can provide thefabrics with good water absorbency. The fabrics preferably also exhibitgood strength, for example good tear strength.

[0023] To provide the crosslinked formaldehyde treatment, the fabric istypically treated with a treatment composition comprising formaldehyde,a catalyst and a silicone elastomer or precursor thereof, followed bydrying and/or curing of the treated fabric. Formaldehyde is generallyavailable in an aqueous solution, referred to as formalin, comprisingwater, about 37% by weight formaldehyde, and generally about 10% to 15%by weight methanol.

[0024] The amount of formaldehyde in the treatment composition ispreferably sufficient to impart a durable press property and/orshrinkage resistance to the fabric. Generally the fabric is treated withat least about 3% by weight formalin, and preferably with from about 3%to about 35% by weight formalin, based on the weight of the fabric. Inone embodiment, for example wherein the fabric comprises cotton fibers,the fabric is treated with about 3% to about 8% formalin, based on theweight of the fabric. In another embodiment, for example wherein thefabric comprises rayon fibers, the fabric is treated with from about 10%to about 20% by weight formalin, based on the weight of the fabric. Inyet another embodiment, for example wherein the fabric comprises a 50/50blend of rayon and polyester fibers, the fabric is treated with fromabout 5% to about 10%, more preferably about 8%, by weight formalin,based on the weight of the fabric. As used herein, “formalin” refers toan aqueous solution comprising 37%, by weight, formaldehyde. As will beapparent to one of skill in the art, formaldehyde solutions comprisinglevels of formaldehyde other than 37%, by weight, may also be used.Using the above ranges of formalin, the fabric is treated with actualformaldehyde, as opposed to formalin, at a level of from about 1% toabout 13%, preferably from about 1% to about 12%, based on the weight ofthe fabric. Thus, in one embodiment, for example wherein the fabriccomprises cotton fibers, the fabric is treated with about 1% to about 3%formaldehyde, as opposed to formalin, based on the weight of the fabric.In another embodiment, for example wherein the fabric comprises rayonfibers, the fabric is treated with from about 4% to about 8% by weightformaldehyde, as opposed to formalin, based on the weight of the fabric.In yet another embodiment, for example wherein the fabric comprises a50/50 blend of rayon and polyester fibers, the fabric is treated withfrom about 2% to about 4%, preferably about 3%, by weight formaldehyde,as opposed to formalin, based on the weight of the fabric.

[0025] Suitable catalysts are those capable of catalyzing across-linking reaction between formaldehyde and a natural fiber, andpreferably are catalysts capable of catalyzing the cross-linking offormaldehyde with a natural fiber comprising hydroxy groups, such ascellulosic fibers. Catalysts which may be used include mineral acids,organic acids, salts of strong acids, ammonium salts, alkylamine salts,metallic salts and combinations thereof. In one embodiment the catalystis other than a mineral acid.

[0026] Suitable mineral acid catalysts include hydrochloric acid,sulfuric acid, nitric acid, phosphoric acid and boric acid. Suitableorganic acids include oxalic acid, tartaric acid, citric acid, malicacid, glycolic acid, methoxyacetic acid, chloroacetic acid, lactic acid,3-hydroxybutyric acid, methane sulfonic acid, ethane sulfonic acid,hydroxymethane sulfonic acid, benzene sulfonic acid, p-toluene sulfonicacid, cyclopentane tetracarboxylic acid, butane tetracarboxylic acid,tetrahydrofuran-tetracarboxylic acid, nitrilotriacetic acid, andethylenediaminetetraacetic acid. Suitable salts of strong acids includesodium bisulfate, sodium dihydrogen phosphate and disodium hydrogenphosphate. Suitable ammonium salts include ammonium chloride, ammoniumnitrate, ammonium sulfate, ammonium bisulfate, ammonium dihydrogenphosphate and diammonium hydrogen phosphate. Suitable alkanolamine saltsinclude the hydrochloride, nitrate, sulfate, phosphate and sulfamatesalts of 2-amino-2-methyl- 1 -propanol, tris (hydroxymethyl)aminomethane and 2-amino-2-ethyl-1-3-propanediol. Suitable metal saltsinclude aluminum chlorohydroxide, aluminum chloride, aluminum nitrate,aluminum sulfate, magnesium chloride, magnesium nitrate, magnesiumsulfate, zinc chloride, zinc nitrate and zinc sulfate, and mixturesthereof.

[0027] In one embodiment of the invention, the catalyst is a halide ornitrate salt of zinc or magnesium, and preferably the catalyst ismagnesium chloride. An organic acid, such as citric acid, may be used incombination with the halide or nitrate salt of zinc or magnesium.Generally the molar ratio of metal salt to organic acid is from about5:1 to about 20:1. In one embodiment, the catalyst comprises magnesiumchloride and citric acid, while in another embodiment the catalystcomprises magnesium chloride and aluminum chloride.

[0028] The fabric is typically treated with an amount of catalystsufficient to catalyze cross-linking of the natural fibers by theformaldehyde. In one embodiment, the catalyst may be employed in anamount sufficient to provide a formaldehyde:catalyst weight ratio offrom about 10:1 to about 1:10, and preferably from about 5:1 to about1:5.

[0029] The formaldehyde treatment composition may comprise, by weight,up to about 12% of a catalyst solution, and preferably from about 1% toabout 9% of a catalyst solution. Generally the catalyst solutioncomprises from about 20% to about 50%, by weight catalyst. In oneembodiment, for example wherein the fabric comprises cotton fibers, thetreatment solution comprises from about 2 to about 4% by weight of acatalyst solution comprising about 30% by weight catalyst, and inanother embodiment, for example wherein the fabric comprises rayonfibers, the treatment solution comprises from about 6% to about 8% byweight of a catalyst solution comprising about 30% by weight catalyst.In yet a further embodiment, the catalyst solution comprises about 40%,by weight, magnesium chloride, for a final magnesium chloride level ofup to about 5%, by weight of the treatment solution. Suitable catalystsolutions include FREECAT® LF (magnesium chloride and citric acid) andFREECAT® No. 9 (aluminum chloride and magnesium chloride), commerciallyavailable from B. F. Goodrich.

[0030] The formaldehyde treatment composition typically comprises aliquid carrier, preferably water, although, as noted above, the formalinused to prepare the treatment composition may comprise small amounts oforganic solvents such as methanol or the like. In one embodiment, thetreatment composition is free of any organic solvents other than thatpresent in the formalin or the catalyst solution. In another embodiment,the carrier may comprise pentamethylcyclosiloxane.

[0031] According to the present methods, a silicone elastomer orprecursor thereof is included in the formaldehyde-containing treatmentcomposition with which the fabric is treated. Thus, the formaldehydetreatment composition comprises formaldehyde, catalyst and siliconeelastomer or a precursor thereof. It has been surprisingly discoveredthat the combination of a silicone elastomer or precursor thereof andthe formaldehyde-containing treatment composition provides the fabricwith reduced ability to retain water and therefore with reduced dryingtimes. The reduced drying times may also be provided in combination withone or more of good water absorbency, good durable press and/orshrinkage resistance properties. This is surprising in that manyconventional treatments which improve one of these properties actuallydegrade other of these desirable properties. Thus, the methods andfabrics of the invention are not only advantageous in providing fabricswith reduced drying times, but also in providing fabrics with reduceddrying times in combination with good water absorbency, good durablepress and/or shrinkage resistance properties. The silicone elastomer mayalso be effective to reduce the loss in tear strength that typicallyoccurs during formaldehyde cross-linking of fibers.

[0032] Various silicone elastomers are known in the art and are suitablefor use in the methods and fabrics of the invention. In one embodiment,the silicone elastomer is a polysiloxane. Similarly, the siliconeelastomer precursor which forms an elastomer upon curing, typically byself curing, may be a polysiloxane. Elastomers are polymers which arecapable of being stretched with relatively little applied force, andwhich return to the unstretched length when the force is released.Silicone elastomers have a backbone made of silicon and oxygen withorganic substituents attached to silicon atoms, with a number n ofrepeating units of the general formula:

[0033] The groups R and Rÿ are each independently selected from loweralkyls, preferably C₁-C₃ alkyls, phenyl, or lower alkyls or phenylscomprising a group reactive to cellulose, such as hydroxy groups,halogen atoms, for example, fluoride, or amino groups. Suitableelastomers include those disclosed in U.S. Pat. No. 5,885,303,incorporated herein by reference.

[0034] A preferred silicone elastomer or precursor composition comprisesup to about 60%, by weight, silicone solids. In one embodiment, thesilicone elastomer or precursor composition comprises from about 20% toabout 60%, preferably from about 30% to about 60%, by weight of siliconesolids, while in another embodiment the silicone elastomer or precursorcomposition comprises from about 20% to about 30% by weight of siliconesolids. Suitable silicone elastomer precursors include a dimethylsilicone emulsion containing from about 30% to about 60%, by weight,silicone solids, commercially available as SM2112 from General Electric.Another suitable commercially available elastomer precursor is SedgesoftELS from Sedgefield Specialties, containing from about 24% to about 26%,by weight, silicone solids.

[0035] When the silicone elastomer or precursor thereof is applied tothe fabric with a liquid formaldehyde treatment composition, the liquidtreatment composition may comprise up to about 10%, preferably fromabout 1% to about 5%, more preferably from about 1% to about 3%, byweight of the elastomer or precursor solids. In one embodiment, thetreatment composition comprises from about 1% to about 3%, preferablyfrom about 1.5% to 3%, by weight silicone solids, while in anotherembodiment, the composition comprises from about 1% to about 1.5% byweight silicone solids.

[0036] The formaldehyde treatment composition may be applied to thefabric in accordance with any of the conventional techniques known inthe art. In one embodiment, the treatment composition may be applied tothe fabric by saturating the fabric in a trough and squeezing thesaturated fabric through pressure rollers to achieve a uniformapplication (padding process). As used herein “wet pick-up” refers tothe amount of treatment composition applied to and/or absorbed into thefabric based on the original weight of the fabric. “Original weight ofthe fabric” or simply “weight of the fabric” refers to the weight of thefabric prior to its contact with the treatment composition. For example,50% pick-up means that the fabric picks up an amount of treatmentsolution equal to 50% of the fabric's original weight. Preferably thewet pick-up is at least 20%, preferably from about 50% to 100%, morepreferably from about 65% to about 80%, by weight of the fabric.

[0037] Other application techniques which may be employed include kissroll application, engraved roll application, printing, foam finishing,vacuum extraction, spray application or any process known in the art.Generally theses techniques provide lower wet pick-up than the paddingprocess. The concentration of the chemicals in the solution may beadjusted to provide the desired amount of chemicals based on theoriginal weight of the fabric (OWF).

[0038] In a preferred embodiment, the formaldehyde treatment compositionis applied in an amount to insure a moisture content of more than 20% byweight, preferably more than 30% by weight, on the fabric before curing.Optionally, a wetting agent may be included in the treatment compositionto facilitate obtaining the desired moisture content. Nonionic wettingagents are preferred.

[0039] Once the treatment composition has been applied to the fabric,the fabric is typically heated for a time and at a temperaturesufficient for the cross-linking of the natural fibers with theformaldehyde. For example, the fabric may be heated at a temperaturegreater than about 250ÿF, preferably from about 250ÿF to about 350ÿF, inan oven for a period of from about 15 seconds to about 15 minutes,preferably from about 45 seconds to about 3 minutes, to react theformaldehyde with the natural fibers in the fabric and affectcrosslinking of the formaldehyde and natural fibers to provide durablepress and/or shrinkage resistance effects. There is an inverserelationship between curing temperature and curing time, that is, thehigher the temperature of curing, the shorter the dwell time in theoven; conversely, the lower the curing temperature, the longer the dwelltime in the oven.

[0040] In another embodiment, the present invention comprises methodsfor reducing the drying time of fabric, wherein the silicone elastomermay be included in the treated fabric by means of a separate treatmentstep before or after the formaldehyde crosslinking treatment.Additionally, if the silicone elastomer or precursor thereof is appliedto the fabric subsequent to treatment with the formaldehyde crosslinkingcomposition, the silicone elastomer precursor thereof may be appliedprior to or subsequent to the heating step which is employed to affectcuring of the formaldehyde with the natural fibers of the fabric,although application prior to heating is preferred. The applied siliconeelastomer or precursor thereof may be dried, with self curing of theprecursor being affected thereby.

[0041] In one embodiment, the fabrics according to the present inventionalso exhibit good water absorbency. As is known in the art, the waterabsorbency of a fabric indicates the ability of the fabric to absorbmoisture, particularly surface moisture, and more specifically, the rateat which surface water is absorbed. As employed in the presentinvention, good water absorbency indicates that the fabric absorbs adrop of water placed thereon, in accord with the methods described inAATCC Method 79-1995, in less than about 100 seconds, even after thefabric has been aqueous laundered at least once. In a more specificembodiment, the fabrics according to the present invention exhibit awater absorbency time, in accord with the methods described in AATCCMethod 79-1995, of less than about 80 seconds, even after the fabric hasbeen aqueous laundered at least once. In yet a further embodiment, thefabrics according to the present invention exhibit a water absorbencytime, in accord with the methods described in AATCC Method 79-1995, ofless than about 60 seconds, even after the fabric has been aqueouslaundered at least once. One skilled in the art will appreciate thatvarious fabric preparation processes may involve application of awetting agent to the fabric. The water absorbency properties asdisclosed herein are exhibited by the fabric after any such wettingagent has been removed, for example by laundering or the like. Thus, thegood water absorbency properties are maintained after one or morewashings or launderings of the fabrics. The good water absorbencyproperties are particularly advantageous when the fabric is used ingarment manufacture, as garments which absorb moisture are generallymore comfortable for wear and therefore are preferred by consumers overgarments which are formed of hydrophobic, non-moisture absorbingfabrics.

[0042] In another embodiment, the fabrics according to the inventionexhibit good durable press properties and/or good shrink resistance. Inone embodiment, it is preferred that the fabric exhibit good durablepress, for example a DP (durable press) rating of at least about 3.0,preferably at least about 3.25, and more preferably at least about 3.5,as measured according to AATCC Test Method 124-1996, after one aqueouswashing, and preferably after five aqueous washings, and/or goodshrinkage resistance, for example a length shrinkage and a widthshrinkage of less than about 10% each, preferably less than about 5%each, more preferably less than about 4% each, and even more preferablyless than about 2% each, and in specific embodiments less than about 1%,as measured according to AATCC Test Method 135-1995, after one aqueouswashing, and preferably after five aqueous washings. Shrinkage may alsobe measured according to AATCC Test Method 150-1995. In furtherpreferred embodiments, the fabrics exhibit good filling tensile and tearstrengths, for example of at least about 25 pounds and at least about 24ounces, respectively, as measured according to ASTM D-5035-95 fortensile strength, and ASTM D-2261-96 for tear strength.

[0043] In another embodiment, cellulose fabrics having a crosslinkedformaldehyde treatment and exhibiting reduced drying times are obtained,provided that the fabric does not comprise 100% cotton. These fabricsmay comprise greater than about 20% cotton fibers, greater than about50% cotton fibers, greater than about 80% cotton fibers, greater thanabout 20% rayon fibers, greater than about 50% rayon fibers, greaterthan about 80% rayon fibers, or about 100% rayon fibers.

[0044] In processes in accordance with the present invention, unreactedformaldehyde remaining on the fabric is removed during subsequentprocessing of the fabric. Generally, the final substrate will compriseless than about 300 ppm formaldehyde, preferably less than about 200 ppmformaldehyde, more preferably less than about 100 ppm formaldehyde, andeven more preferably less than about 50 ppm formaldehyde, as measuredaccording to AATCC Test Method 112-1993.

[0045] Some polysiloxanes, generally referred to as silicone oils, havea liquid form, are not elastomeric and do not self-crosslink. Siliconeoils include, for example, non-reactive linear polydimethyl siloxanes,that is, siloxanes which are not capable of further reaction with othersilicones and are not capable of a self curing reaction. Silicone oilshave a tendency to produce non-removable spots on fabrics. In contrast,the silicone elastomers used in the present invention generally do notproduce such spots. Although the fabrics or treatment compositions maycomprise silicone oil, in one embodiment, the fabrics and treatmentcompositions are substantially free of, and preferably are free of,silicone oil. As used herein, substantially free of silicone oils meansthe treatment compositions and fabrics comprise less than 1%, by weight,silicone oil.

[0046] Thermosetting resins used to impart durable press properties tofabrics are generally aminoplast resins which are the products of thereaction of formaldehyde with compounds such as urea, thiourea, ethyleneurea, dihydroxyethylene urea and melamines. As used herein “aminoplastresins” is intended to include N-methylolamide cross-linking agents suchas dimethylol dihydroxyethylene urea, dimethylol urea,dimethylolethylene urea, dimethylol propylene urea, dimethylol methylcarbamate, dimethylol n-propylcarbamate, dimethylol isopropylcarbamatetrimethylolated melamine, and tris(methoxymethol) melamine. Preferably,the fabrics, methods and formaldehyde treatment compositions of theinvention are substantially free of, and more preferably are free of,aminoplast resins, including those aminoplast resins containing orformed from N-methylol cross-linking agents. As used herein,“substantially free” of aminoplast resins is intended to mean thefabrics and treatment solutions comprise less than about 0.5%, byweight, aminoplast resin or methylol cross-linking agent.

[0047] Prior to treatment with the formaldehyde composition and siliconeelastomer or precursor thereof, the fabric may optionally be preparedusing any fiber, yarn, or textile pretreatment preparation techniquesknown in the art. Suitable preparation techniques include brushing,singeing, desizing, scouring, mercerizing, and bleaching. For example,fabric may be treated by brushing which refers to the use of mechanicalmeans for raising surface fibers which will be removed during singeing.The fabric may be then be singed using a flame to burn away fibers andfuzz protruding from the fabric surface. Textiles may be desized, whichrefers to the removal of sizing chemicals such as starch and/orpolyvinyl alcohol, that are put on yams prior to weaving to protectindividual yams. The fabrics may be scoured, which refers to the processof removing natural impurities such as oils, fats and waxes andsynthetic impurities such as mill grease from fabrics. Mercerizationrefers to the application of high concentrations of sodium hydroxide toa fabric to alter the morphology of fibers, particularly cotton fibers.Fabrics may be mercerized to improve fabric stability and luster.Finally, bleaching refers to the process of destroying any natural colorbodies within the natural fiber. A typical bleaching agent is hydrogenperoxide.

[0048] The various preparation techniques are optional and dependentupon the desired final product. For example, when the final fabric is tobe dyed a dark color, there may be no need to bleach the substrate.Similarly, there may be no need to desize a knit which was preparedwithout using any sizing agents, and no need to separately scour knitsand woven textiles as the scouring may be done during bleaching.

[0049] The following examples are set forth to demonstrate the methodsof the present invention and the reduced drying times which are obtainedin fabrics by the methods of the present invention. Throughout theexamples and the present specification, parts and percentages are byweight unless otherwise specified. The following examples areillustrative only and are not intended to limit the scope of the methodsand fabrics of the invention as defined by the claims.

EXAMPLE 1

[0050] In this example, men's shirts are formed of a fabric whichcomprises an 85/15 blend of rayon/flax provided with a formaldehydecrosslinking treatment in accordance with the invention. Generally, eachfabric is contacted with an aqueous solution comprising about 10% to 20%formalin, a weight ratio of formalin to catalyst solution of about 18:5,and about 3% (solids) of a silicone elastomer commercially availablefrom General Electric under the designation GE SM2112. The aqueoussolution is padded on the fabric to provide a moisture content ofgreater than about 30% and the treated fabric is heated at a temperaturegreater than about 300° F. for a period of time sufficient to effectcrosslinking of the formaldehyde with the cellulose in the rayon andflax fibers.

[0051] The resulting fabric samples and untreated control samples of thefabric are run through a conventional home laundry cycle. Both treatedand untreated wet fabric samples are subjected to drying in a dryer. Thetreated fabric samples dry in about 20 minutes while the untreatedsamples dry in about 50 minutes. Additionally, garments formed of thetreated and untreated fabric, respectively, are subjected toconventional line drying. The treated garments dry in about 3 hourswhile the untreated garments dry in about 5 hours. For furthercomparison, conventional aminoplast resin-treated samples and garmentsof the fabric are similarly run through a conventional home laundrycycle and subjected to machine drying and line drying, respectively. Theresin-treated samples dry in about 30 minutes in the machine dryer whilethe resin-treated garments dry in about 4 hours on the line. Thus, thefabrics and garments according to the present invention exhibit reduceddrying times as compared with untreated fabrics and garments and ascompared with conventional aminoplast resin treated fabrics andgarments.

EXAMPLE 2

[0052] In this example, fabric swatches are provided with a formaldehydecrosslinking treatment in accordance with the invention. A first type offabric swatch samples, fabric 1 comprising an 85/15 rayon/flax blend,are treated in accordance with the general process described inExample 1. A second set of fabric swatch samples, fabric 2 comprising100% cotton shirting fabric, are treated in a similar manner wherein theaqueous solution comprises about 3% to about 8% formalin, based on theweight of the fabric. The fabric swatch samples treated according to theinvention, untreated fabric swatch samples of the same fabrics andfabric swatch samples of the fabrics which are treated with aconventional aminoplast resin treatment are washed in a home washer ofthe type typically found in the United States and then subjected totumble drying in a home dryer. During the drying processes, theprocesses are interrupted and the various fabric samples are weighed todetermine their weight relative to the respective fabric sample swatchesprior to washing. In a first set of experiments, the fabric swatchsamples are washed with a combination of liquid Tide® Free and Downy®Premium Care (wash 1). In a second set of experiments, fabric swatchsamples are washed with a combination of liquid Tide® Free and Downy®Regular-Unscented (wash 2). At least three swatches of each fabricsample are tested, with the average weight of the fabric samples as apercentage of the original weight 1) after washing but before anydrying, 2) after 10 minutes of drying, and 3) after 20 minutes ofdrying, being set forth in Table 1. TABLE 1 Weight of Fabric Swatch asPercentage of Prewash Weight Fabric Swatch Sample/Wash % of original wt,% of original wt, % of original wt, Sample process before drying after10 min drying after 20 min drying 2A 1-untreated/wash 1 183.1 125.7 94.92B 1-conventional resin/wash 1 143.8 104.6 94.0 2C 1-inventive/wash 1142.5 96.0 94.0 2D 2-untreated/wash 1 134.6 95.0 — 2E 2-conventionalresin/wash 1 131.7 95.5 — 2F 2-inventive/wash 1 130.6 97.1 — 2G1-untreated/wash 2 182.8 116.1 92.1 2H 1-conventional resin/wash 2 159.2107.5 97.4 2I 1-inventive/wash 2 133.8 94.7 93.2 2J 2-untreated/wash 2148.2 111.2 101.9 2K 2-conventional resin/wash 2 130.3 98.0 95.1 2L2-inventive/wash 2 142.5 107.8 103.3

[0053] The results set forth in Table 1 demonstrate that the fabricsamples 2C, 2F, 2I and 2L according to the invention contain less waterprior to any drying and dry more quickly as compared with the untreatedfabric samples 2A, 2D, 2G and 2J. The improvements in reduced dryingtime are particularly evident with respect to fabric swatch samples offabric 1 which comprise the rayon/flax blends. Additionally, the fabricswatch samples according to the present invention exhibit substantiallysimilar or better drying times as compared with the conventionalresin-treated samples.

[0054] Fabric samples 2A-2C are also evaluated to determine their waterretention according to ASTM 2402-94, Water Retention of Textile Fibers(Centrifuge Method). Samples 2A, 2B and 2C exhibited water retention of113%, 90% and 53%, respectively. Thus, the fabric treated according tothe invention desirably exhibited the lowest water retention. Fabricstreated according to the methods of the invention typically exhibitreductions in water retention of greater than about 20%, morespecifically greater than about 30%, and in some cases greater thanabout 40%, as compared with untreated fabrics and/or conventionalresin-treated fabrics.

EXAMPLE 3

[0055] In this example, fabric swatch samples as described in Example 2are subjected to washing in a Miele washer of the type typicallyemployed in Europe, followed by line drying in order to evaluate theline drying times of the respective fabrics. At least three swatches ofeach fabric are tested, with the average weight of the fabric swatchesduring drying being set forth as a percentage of prewash weight in Table2. The weight percentage values in Table 2 are normalized based on thefinal weight of the fabric after 60 minutes of drying. TABLE 2 Weight ofFabric Swatches as Percentage of Final Weight Fabric Swatch % oforiginal wt, % of original wt, % of original wt, after % of original wt,after Sample Sample/Wash process before drying after 20 min drying 40min drying 60 min drying 3A 1-untreated 166.6 135.2 114.0 100 3B1-conventional resin 136.1 108.1 101.4 100 3C 1-inventive 125.2 102.1100.7 100 3D 2-untreated 129.2 102.6 100.5 100 3E 2-conventional resin128.3 101.5 100.4 100 3F 2-inventive 129.1 101.5 100.1 100

[0056] As in Example 2, the fabric samples 3C and 3F of this inventionexhibit reduced drying times as compared with the untreated fabricsamples 3A and 3D. The reductions in drying times exhibited by thefabric samples according to the present invention are particularlyevident in the rayon/flax samples.

EXAMPLE 4

[0057] In this example, a fabric swatch comprising 100% cotton jersyknit is provided with a formaldehyde crosslinking treatment inaccordance with the invention and the general process described inExample 1 wherein the aqueous solution comprises about 5% formalin,based on the weight of the fabric. The fabric swatch sample, anuntreated control fabric swatch sample and an untreated, mechanicallyfinished fabric swatch sample are washed in a home washer of the typetypically found in the United States and then subjected to tumble dryingin a home dryer. During the drying processes, the processes areinterrupted and the fabric samples are weighed to determine their weightrelative to the respective fabric sample swatches prior to washing. Theresults are set forth in Table 3. TABLE 3 % of original % of original %of original % of original % of original Fabric Swatch wt, before wt,after 5 min wt, after 10 min wt, after 15 min wt, after 20 min SampleSample drying drying drying drying drying 4A Treated 194 174 145.8 109.2105.5 4B Untreated Control 223 197 170 112.5 97.7 4C Mechanically 234202.5 171 116 98 Finished

[0058] The results set forth in Table 3 demonstrate that the treatedfabric sample 4A according to the invention contains less water prior toany drying and dries more quickly as compared with the untreated fabricsample 4B or the untreated mechanically finished sample 4C.

[0059] The treated fabric sample 4A and untreated control fabric sample4B are also evaluated for water retention according to ASTM 2402-94. Thetreated fabric sample 4A exhibits a water retention of 67.4% while theuntreated control fabric sample 4B exhibits a water retention of 96.5%.

EXAMPLE 5

[0060] In this example, various fabrics are provided with a formaldehydecrosslinking treatment in accordance with the invention and the generalprocess described in Example 1 wherein the aqueous solution comprises anamount of formalin as set forth in Table 4, based on the weight of thefabric. The fabric samples and conventional resin-treated samples of thefabrics are washed in a home washer of the type typically found in theUnited States and then subjected to tumble drying in a home dryer.During the drying processes, the processes are interrupted and thevarious fabric samples are weighed to determine their weight relative tothe respective fabric sample swatches prior to washing. The fabricsamples are also evaluated for water retention according to ASTM2402-94. The results are set forth in Table 4. TABLE 4 Water Retentionand Weight of Fabric Swatch as Percentage of Prewash Weight % oforiginal % of original % of original % of original Fabric Type/ PercentWater wt, before wt, after 5 min wt,after 10 min wt,after 15 min SampleTreatment Retention drying drying drying drying 5A Viscose/ 65.1 150 129102 99 Formalin (20%) 5B Viscose/ 77.8 184 160 122 100 Resin 5CProviscose/ 58.1 156 127 104 101 Formalin (20%) 5D Proviscose/ 85.3 175154 116 99 Resin 5E 50/50 56.4 ** ** ** ** Cotton/Modal/ Formalin (20%)5F 50/50 67.0 ** ** ** ** Cotton/Modal/ Resin 5G Modal/Formalin 57.2 151125 103 101 (20%) 5H Modal/ 70.6 159 140 108 100 Resin 5ILyocell/Formalin 55.5 ** ** ** ** (18%) 5K 55/45 Lyocell/ 51.1 ** ** **** Polyester/ Formalin (18%) 5L 55/45 Lyocell/ 43.9 ** ** ** **Polyester/ Resin 5M 75/25 Rayon/ 65.5 175 161 134 101 Polyester/Formalin (18%) 5N 75/25 Rayon/ 108.2 213 191 159 109 Polyester/ Resin

[0061] The results set forth in Table demonstrate that the treatedfabric samples 5A, 5C, 5E, 5G, 5I, 5K and 5M according to the inventionretain less water and/or contain less water prior to any drying and drymore quickly as compared with the resin-treated fabric samples 5B, 5D,5F, 5H, 5J, 5L and 5M.

[0062] The examples and specific embodiments set forth herein are forillustrative purposes only and are not intended to limit the scope ofthe methods and fabrics of the invention. Additional methods and fabricswithin the scope of the claimed invention will be apparent to one ofordinary skill in the art in view of the teachings set forth herein.

What is claimed is:
 1. A method for reducing the drying time of fabric,comprising treating the fabric with a treatment composition comprisingformaldehyde, catalyst for crosslinking the formaldehyde with naturalfibers in the fabric, and silicone elastomer or a precursor thereof, andheating the treated fabric to effect crosslinking of the formaldehyde.2. A method according to claim 1 , wherein the fabric comprises at leastabout 50% by weight of cellulose fibers.
 3. A method according to claim1 , wherein the treatment composition consists essentially offormaldehyde, catalyst and silicone elastomer or a precursor thereof. 4.A method according to claim 1 , wherein the treatment composition isfree of aminoplast resin.
 5. A method according to claim 1 , wherein thetreatment composition comprises a silicone elastomer precursor.
 6. Amethod for reducing the drying time of fabric while providing the fabricwith good water absorbency and durable press properties, comprisingtreating the fabric with a treatment composition comprisingformaldehyde, catalyst for crosslinking the formaldehyde with naturalfibers in the fabric, and silicone elastomer or a precursor thereof, andheating the treated fabric to effect crosslinking of the formaldehyde.7. A method according to claim 6 , wherein the resulting fabric exhibitsa water absorbency time of less than about 100 seconds as measuredaccording to AATCC Method 79-1995 after the fabric has been aqueouslaundered at least one time, a durable press value of at least about 3after the fabric has been aqueous laundered at least one time, and/or alength shrinkage and a width shrinkage of less than about 5% each afterthe fabric has been aqueous laundered one time.
 8. A method for reducingthe drying time of fabric while providing the fabric with good waterabsorbency and shrinkage resistance properties, comprising treating thefabric with a treatment composition comprising formaldehyde, catalystfor crosslinking the formaldehyde with natural fibers in the fabric, andsilicone elastomer or a precursor thereof, and heating the treatedfabric to effect crosslinking of the formaldehyde.
 9. A method accordingto claim 8 , wherein the fabric comprises at least about 50% by weightof rayon fibers.
 10. A method according to claim 8 , wherein thetreatment composition consists essentially of formaldehyde, catalyst andsilicone elastomer or a precursor thereof.
 11. A method according toclaim 8 , wherein the treatment composition is free of aminoplast resin.12. A method according to claim 8 , wherein the treatment compositioncomprises a silicone elastomer precursor.
 13. A method according toclaim 16 , wherein the resulting fabric exhibits a water absorbency timeof less than about 100 seconds as measured according to AATCC Method79-1995 after the fabric has been aqueous laundered at least one time, adurable press value of at least about 3 after the fabric has beenaqueous laundered at least one time, and/or a length shrinkage and awidth shrinkage of less than about 5% each after the fabric has beenaqueous laundered one time.
 14. A method of reducing the drying time offabric, comprising crosslinking cellulose in the fabric withformaldehyde and providing the fabric with a silicone elastomer.
 15. Amethod for reducing the drying time of fabric, comprising treating thefabric with a treatment composition comprising formaldehyde and catalystfor crosslinking the formaldehyde with natural fibers in the fabric,treating the fabric with silicone elastomer or a precursor thereof, andheating the treated fabric to effect crosslinking of the formaldehyde.16. Fabric comprising natural fibers, having a crosslinked formaldehydetreatment and being provided with a silicone elastomer, wherein thefabric exhibits a reduced drying time, wherein the fabric does notcomprise 100% cotton.
 17. Fabric according to claim 16 , wherein thefabric exhibits a water absorbency time of less than about 100 secondsas measured according to AATCC Method 79-1995 after the fabric has beenaqueous laundered at least one time, a length shrinkage and a widthshrinkage of less than about 5% each after the fabric has been aqueouslaundered at least one time, and/or a durable press value of at leastabout 3 after the fabric has been aqueous laundered at least one time.18. Fabric comprising rayon fibers and exhibiting a reduced drying time.19. Fabric according to claim 18 , wherein the fabric exhibits a waterabsorbency time of less than about 100 seconds as measured according toAATCC Method 79-1995 after the fabric has been aqueous laundered atleast one time, a length shrinkage and a width shrinkage of less thanabout 5% each after the fabric has been aqueous laundered at least onetime, and/or a durable press value of at least about 3 after the fabrichas been aqueous laundered at least one time.